De jure (in Classical Latin de iure) is an expression that means "by law", as contrasted with de facto, which means "in fact".
The terms de jure and de facto are used like "in principle" and "in practice" when one is describing political situations. They are also often used when discussing racial segregation. A practice may exist de facto, where the people obey a contract as though there were a law. A process known as "desuetude" may allow de facto practices to become law. On the other hand, practices may exist de jure and not be obeyed or observed by the people.
The Latin de jure should not be confused with the French du jour which translates to "of the day", as, for example, in soupe du jour.
See also